U.S. patent number 7,586,069 [Application Number 10/800,062] was granted by the patent office on 2009-09-08 for inner box for cooker and method of integrating the same.
This patent grant is currently assigned to Panasonic Corporation. Invention is credited to Susumu Idomoto, Takahiro Inoue, Kiyoto Ishida.
United States Patent |
7,586,069 |
Inoue , et al. |
September 8, 2009 |
**Please see images for:
( Certificate of Correction ) ** |
Inner box for cooker and method of integrating the same
Abstract
An inner box for a cooker is provided including a front plate
having an opening portion and an inner box main body bonded to a
peripheral edge of the opening portion comprising a first
fold-to-bend portion constituted by folding to bend an end portion
thereof to invert to be brought into close contact therewith and a
second fold-to-bend portion constituted by inverting a portion on a
side of the end portion of the first fold-to-bend portion with a
predetermined clearance therebetween and a flange portion inserted
into the clearance between the first fold-to-bend portion and the
second fold-to-bend portion, and wherein the bonding portions of
the front plate and the inner box main body are constituted by a
structure of inserting the flange portion into the clearance to be
calked to bond therewith.
Inventors: |
Inoue; Takahiro (Nara,
JP), Ishida; Kiyoto (Yamatokooriyama, JP),
Idomoto; Susumu (Yamatokooriyama, JP) |
Assignee: |
Panasonic Corporation (Osaka,
JP)
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Family
ID: |
33285622 |
Appl.
No.: |
10/800,062 |
Filed: |
March 12, 2004 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20040232134 A1 |
Nov 25, 2004 |
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Foreign Application Priority Data
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Mar 13, 2003 [JP] |
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P. 2003-068221 |
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Current U.S.
Class: |
219/756;
126/273R; 219/738; 219/739 |
Current CPC
Class: |
F24C
15/08 (20130101) |
Current International
Class: |
H05B
6/64 (20060101) |
Field of
Search: |
;219/756,738,752,739,685,704,762,751,401,402,404
;220/619,620,431,689 ;126/273R,21R,19R,190,200 ;29/509,513,521 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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59-172904 |
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Nov 1984 |
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JP |
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6099404 |
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Jul 1985 |
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JP |
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60259832 |
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Dec 1985 |
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JP |
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264810 |
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May 1990 |
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JP |
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02179324 |
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Jul 1990 |
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JP |
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Other References
Japanese Office action with English translation. cited by
other.
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Primary Examiner: Van; Quang T
Attorney, Agent or Firm: Pearne & Gordon LLP
Claims
What is claimed is:
1. An inner box for a cooker, comprising: a front plate having an
opening portion; and an inner main body bonded to a peripheral edge
of the opening portion for cooking at inside of the inner main
body; wherein at least either one of bonding portions of the front
plate and the inner main body includes a first fold-to-bend portion
constituted by folding to bend an end portion thereof to invert to
be brought into close contact therewith, and a second fold-to-bend
portion constituted by inverting a portion on a side of an end
portion of the first fold-to-bend portion with a predetermined
clearance therebetween, and wherein other of the bonding portions
of the front plate and the inner main body includes a flange
portion inserted into the clearance between the first fold-to-bend
portion and the second fold-to-bend portion, and calked to bond,
wherein the second fold-to-bend portion has a locking hole and the
flange portion has a locking projection that extends through the
locking hole, wherein insulating films are formed on a surface of
the front plate on a side opposed to a side of being connected with
the inner main body and an outer side surface of the inner main
body, and wherein an inner peripheral portion of the locking hole
is not formed with the insulating film and constitute a conducted
face, and a surface of the main body portion of the locking
projection is a metal face having conductivity, and wherein the
locking projection is formed on the surface on which the insulating
films are not formed, and therefore a front plate and a face plate
of the inner box main body are electrically connected.
2. An inner box for a cooker, comprising: a front plate having an
opening portion; and an inner main body bonded to a peripheral edge
of the opening portion for cooking at inside of the inner main
body; wherein at least either one of bonding portions of the front
plate and the inner main body includes a first fold-to-bend portion
constituted by folding to bend an end portion thereof to invert to
be brought into close contact therewith, and a second fold-to-bend
portion constituted by inverting a portion on a side of an end
portion of the first fold-to-bend portion with a predetermined
clearance therebetween, and wherein other of the bonding portions
of the front plate and the inner main body includes a flange
portion inserted into the clearance between the first fold-to-bend
portion and the second fold-to-bend portion, and calked to bond,
wherein the second fold-to-bend portion has a locking hole and the
flange portion has a locking projection that extends through the
locking hole, wherein the locking projection is a projection formed
by punching machining, wherein insulating films are formed on a
surface of the front plate on a side opposed to a side of being
connected with the inner main body and an outer side surface of the
inner main body, and wherein an inner peripheral portion of the
locking hole is not formed with the insulating film and constitute
a conducted face, and a surface of the main body portion of the
locking projection is a metal face having conductivity, and wherein
the locking projection is formed on the surface on which the
insulating films are not formed, and therefore a front plate and a
face plate of the inner box main body are electrically connected.
Description
BACKGROUND OF THE INVENTION
The present invention relates to an inner box for a cooker formed
by bonding a plurality of sheets of plate members, particularly
relates to an improvement in a bonding portion of a face plate.
Conventionally, a plate constitution of an inner box for a cooker
is constituted by a front plate 51 having an opening portion, a
rear plate 53, an inner box main body 55 provided between the front
plate 51 and the rear plate 53, and a ceiling plate 57 covering
from an upper face thereof as generally shown by FIG. 9.
In such an inner box main body 55, as shown by a bonding portion
for bonding the front plate 51 and a face plate 61 of the inner box
main body 55 in FIG.10(a), an end edge of the opening portion of
the front plate 51 is formed with a fold-to-bend portion 59, and a
fold-to-bend portion 63 constituting a V-like shape relative to a
face of the front plate 51 and skewedly projected to the face plate
61 of the inner box main body 55 is formed from the fold-to-bend
portion 59. Meanwhile, also at an end portion of the face plate 61
of the inner box main body 55, similar to the front plate 51, an
end edge thereof is formed with a fold-to-bend portion 65 and a
front end portion 65a thereof is arranged on an inner side of the
fold-to-bend portion 63 to prepare for a calking step.
Further, as shown by FIG. 10(b), in the calking step, in a state of
supporting a lower side in the drawing of the front plate 51, while
inserting the front end portion 65a of the fold-to-bend portion of
the face plate 61 into a space between the fold-to-bend portion 63
of the front plate 51 and the front plate 51, a calking jig, not
illustrated, is pressed from above the face plate 61 to the front
plate 51 over an entire periphery of the bonding portion for
bonding the face plate 61 and the front plate 51. Thereby, the
fold-to-bend portion 63 of the front plate 51 and the fold-to-bend
portion 65 of the face plate 61 are brought into close contact with
each other by being sandwiched by each other to thereby fix the
front plate 51 and the face plate 61 of the inner box main body by
end calking (refer to, for example, Japanese Utility Model
Publication JP-UM-A-59-172904).
However, according to the above-described inner box for a cooker,
four sheets of the face plates 61 to be bonded with the front plate
51 of the inner box main body 55 are simultaneously calked to bond
to the front plate 51 and therefore, a pressure applied to the
calking jig is considerable, further, also an equipment for the
calking step becomes large-sized. Therefore, when the face plates
61 are successively bonded to the front plate 51 sheet by sheet
instead of simultaneously calking to bond four sheets of the face
plates 61 thereto, the calking step can be carried out simply and
conveniently without applying the considerable pressure on the
calking jig, however, a bonding structure having the
above-described constitution poses the following problem.
That is, in pressing the face plate 61 of the inner box main body
55 by the calking jig, there is a play between the respective
fold-to-bend portions 63, 65 in a pressing direction of the front
plate 51 in calking, that is, both of the fold-to-bend portions 63,
65 are projected in height directions and therefore, a slide amount
.DELTA.H in the pressing direction of the face plate 61 is
prolonged by pressing in calking. Therefore, when the calking step
is carried out in a state of respectively dividing four sheets of
the face plates 61 to be bonded with the front plate 51 of the
inner box main body 55, the above-described difference in height of
.DELTA.H is produced between the face plate after the calking step
and the face plate before the calking step contiguous thereto. By
the difference in height, warping is produced in the inner box main
body 55 bonded with four sheets of the face plates and also the
front plate 51 is bent. When the calking step is continued in a
state in which the respective face plates and the front plate are
respectively bent in this way, the inner box 55 is finished in a
state of the inner box 55 being warped, bent are buckled.
Further, there is a case of carrying out a surface treatment of,
for example, precoated metal (PCM) or the like on a surface of the
front plate 51 and surfaces of the respective face plates 61 of the
inner box 55 to meet a request of promoting a beautiful outlook in
household electric appliances in recent times. In this case, since
the precoated metal is provided with insulating performance, when
the faces which are brought into close contact with each other by
the calking step are constituted only by insulating faces, the
respective face plates 61 are brought into an unconducted state and
when a high frequency wave is irradiated into the inner box 55 for
cooking, radio wave shielding of the inner box 55 becomes
incomplete and leakage of radio wave is brought about. Therefore,
shapes of the fold-to-bend portions 63, 65 are restricted in view
of design since the respective face plates 61 need to be connected
electrically.
SUMMARY OF THE INVENTION
The invention has been carried out in order to resolve the
above-described problem and it is an object there of to provide an
inner box for a cooker capable of firmly carrying out a calking
step for bonding by simple operation without requiring a
large-sized equipment and capable of being integrated without a
drawback of leakage of radio wave or the like at low cost and a
method of integrating the same.
The above-described object is achieved by a constitution shown
below.
(1) An inner box for a cooker which is an inner box for a cooker
including a front plate having an opening portion and an inner box
main body bonded to a peripheral edge of the opening portion for
cooking at inside of the inner box main body,
wherein at least either one of the bonding portions of the front
plate and the inner box main body is formed with a first
fold-to-bend portion constituted by folding to bend an end portion
thereof to invert to be brought into close contact therewith and a
second fold-to-bend portion constituted by inverting a portion on a
side of an end portion of the first fold-to-bend portion with a
predetermined clearance therebetween, other of the bonding portions
of the front plate and the inner box main body is formed with a
flange portion inserted into the clearance between the first
fold-to-bend portion and the second fold-to-bend portion, and the
bonding portions are constituted by a structure in which the flange
portion is inserted into the clearance to be calked to bond.
According to the inner box for a cooker, the flange portion on
other side is arranged to the clearance between the first
fold-to-bend portion and the second fold-to-bend portion on one
side to be bonded and calked to bond therewith to thereby fix the
front plate and the inner box main body to be sandwiched to fix by
the bonding portions. Therefore, the face plates of the inner box
main body are calked to bond with the front plate at positions at
which the face plates of the inner box main body are brought into
contact with the front plate and a positional shift is hardly
produced between the face plates and the front plate between before
calking and after calking. Further, the face plates and the front
plate are dividedly calked to bond without being calked to the
entire periphery of the bonding portion in one motion by large
pressure and therefore, bonding is carried out by comparatively
small pressure. Therefore, the integrating process can be
simplified without needing a large amount of equipment
investment.
(2) In the inner box for a cooker, the second fold-to-bend portion
may be formed with a locking hole and the flange portion is formed
with a locking projection inserted into the locking hole.
According to the inner box for a cooker, a shift in the bonding
position is difficult to be brought about by the locking hole at
the second fold-to-bend portion on one side to be bonded and the
locking projection at the flange portion on other side.
(3) The locking projection may be a projection formed by
punching.
According to the inner box for a cooker, a dowel can be formed by
simple pressing without attaching a member separately.
(4) Further, insulating films maybe formed on a surface of the
front plate on a side opposed to a side of being connected with the
inner box main body and an outer side surface of the inner box main
body.
According to the inner box for a cooker, even when an electrically
insulating surface treatment is carried out on the surface of the
front plate or the inner box main body, a conductive path is formed
and a radio wave shielding effect can be achieved without being
influenced by the electrically insulating surface treatment
coating. Further, by bringing the locking projection into face
contact with an inner peripheral face of the locking hole by
calking to bond, conduction can firmly be ensured.
(5) According to the present invention, in a method of integrating
the inner box for a cooker, end portions of face plates of the
inner box main body connected to the front plate are bonded to the
front plate individually for the respective face plates.
According to the method of integrating the inner box for a cooker,
the inner box main body is not warped, further, the calking step
can be carried out without requiring a large-sized equipment and
fabricating cost can be restrained.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partially disassembled outlook perspective view of an
inner box for a cooker according to a first embodiment of the
invention.
FIG. 2 is a partially enlarged view of the inner box for a cooker
shown in FIG. 1 before a calking step.
FIG. 3 is a sectional view taken along a line A-A of FIG. 2.
FIG. 4 is a sectional view showing a behavior after the calking
step of FIG. 2.
FIG. 5 is a partially disassembled outlook perspective view showing
a state of a bonding portion after calking.
FIG. 6 is a disassembled view of an inner box for a cooker.
FIG. 7 is an explanatory view showing an example of bonding an
inner box main body and a ceiling plate.
FIG. 8 is a sectional view of an example of constituting a locking
projection formed at a flange portion by a drawn round hole
projection.
FIG. 9 is a conceptual perspective view showing a plate
constitution of an inner box for a cooker of a prior art.
FIGS.10(a) and 10(b) illustrate views showing a calking step of the
conventional art, FIG. 10(a) is an explanatory view showing a state
before being calked to bond and FIG. 10(b) is an explanatory view
showing a state after being calked to bond.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A detailed explanation will be given of an embodiment of an inner
box for a cooker according to the invention and a method of
integrating the same in reference to the drawings as follows.
FIG. 1 is a partially disassembled outlook perspective view of an
inner box for a cooker according to a first embodiment of the
invention, FIG. 2 is a partially enlarged view of the inner box for
a cooker shown in FIG. 1 before a calking step, and FIG. 3 is a
sectional view taken along a line A-A of FIG. 2.
As shown by FIG. 1, an inner box 100 for a cooker according to the
first embodiment of the invention is constituted by including an
inner box main body 23 comprising a front plate 13 having an
opening portion 11, a bottom plate 15, a ceiling plate 17, a rear
plate 19, and a side plate 21, and when the inner box 100 is formed
as a heating chamber of a high frequency cooker as an example of a
cooker, the inner box 100 becomes a box member for heating an
object to be heated contained at inside of the inner box by
irradiating a high frequency wave into the inner box.
The front plate 13 is opposed to an opening/closing door, not
illustrated, for closing the opening portion 11 (an inserting port
of the object to be heated) and is formed with the opening portion
11 at a central portion thereof. A peripheral edge portion of the
opening portion 11 is formed with a first fold-to-bend portion 25
constituted by folding to bend to invert an end portion thereof to
be brought into close contact with the front plate 13, and a second
fold-to-bend portion 27 constituted by inverting a portion of an
end portion side of the first fold-to-bend portion 25 with a
predetermined clearance therebetween. Thereby, the first
fold-to-bend portion 25 and the second fold-to-bend portion 27 are
formed substantially in U-shape. A bonding portion 28 of the
faceplate 13 is calked to bond with four sheets of the face plates
(the bottom plate 15, the ceiling plate 17, and the respective side
plates 21) of the inner box main body 23.
FIG. 2 shows a conceptual partially enlarged disassembled view of
before calking the bonding portion bonded with the inner box main
body at the peripheral edge portion of the front plate 13.
An inverted portion 25a of the first fold-to-bend portion 25 is
brought into close contact with the front plate 13 to promote a
rigidity by an increase in a modulus of section. The second
fold-to-bend portion 27 is inclined relative to the front plate 13
to open a clearance 29 in a state before calking. Further, the
second fold-to-bend portion 27 is formed with a plurality of
locking holes 31 in shapes of long holes which act as dowel holes
at predetermined intervals along a direction of a peripheral edge
of the bonding portion 28.
Meanwhile, a bonding portion of the face plate on a side of the
inner box main body 23 is formed with a flange portion 33 inserted
into the clearance 29 between the first fold-to-bend portion 25 and
the second fold-to-bend portion 27 of the front plate 13. Further,
the flange portion 33 is provided with a plurality of locking
projections 35 which act as dowels in correspondence with the
locking holes 31 on a side of the front plate 13. According to the
locking projection 35, the projection can simply be formed by
punching by pressing or the like from a rear face (lower side in
the drawing) of the flange portion 33.
FIG. 3 shows a section taken along a line A-A of FIG. 2 when the
front plate and the inner box main body are integrated. According
to the face plate of the inner box main body 23, a position of the
face plate of the inner box main body 23 in a B direction relative
to the front plate 13 is restricted by inserting the flange portion
33 of the bonding portion 28 into the clearance 29 between the
first fold-to-bend portion 25 and the second fold-to-bend portion
27 to press in the B direction of the drawing. Further, by pressing
a calking jig 37 in a direction of bonding the both under the
state, the second fold-to-bend portion 27 of the front plate 13 is
pressed to the side of the front plate 13 by fitting to insert the
locking projections 35 of the flange portion 33 into the locking
holes 31. As shown by FIG. 4, by the calking step, according to the
front plate 13 and the face plate of the inner box main body, the
first fold-to-bend portion 25, the flange portion 33, and the
second fold-to-bend portion 27 are brought in to close contact with
each other and bonded together substantially in parallel with each
other. The locking projections 35 of the flange portion 33 are
spread in the locking holes 31 by a pressure and inner peripheral
faces of the locking holes 31 and the locking projections 35 are
brought into face contact with each other to prevent from being
drawn out. Further, by forming the locking hole 31 in the shape of
the long hole, a dimensional error in sheet metal drawing is
permitted.
FIG. 5 shows a state of the bonding portion after calking by a
perspective view. When the inner box 10 is used in a high frequency
cooker, by constituting a pitch P in the peripheral edge direction
of the locking projections 35 and the locking holes 31 to be equal
to or smaller than 1/4 of a wave length of a high frequency wave,
the leakage of radio wave to outside of the box can be
prevented.
Further, when the inner box 10 is used for a high frequency cooker,
in order to achieve a radio wave shielding effect at inside and
outside of the box, the respective face plates need to conduct and
for that purpose, the bonding portions between the respective face
plates need to electrically conduct. However, one surface of each
of the front plate 13 and the face plates of the inner box main
body 23 is formed with a surface treatment coating having an
electrically insulating property of a precoated metal or the like,
according to the above-described integrating method of integrating
the flange portion 33 into the clearance 29 between the first
fold-to-bend portion 25 and the second fold-to-bend portion 27,
both of the front plate 13 and the face plates of the inner box
main body 23 are brought into contact with each other on sides of
insulating faces thereof to bring about an unconducted state.
Hence, the both can be brought into a conducted state by providing
the locking holes 31 and the locking projections 35 inserted there
into as shown by FIG. 4.
That is, the inner peripheral face of the locking hole 31 shown in
FIG. 4 is not formed with a surface treatment coating (insulating
film) 41 to constitute a conducted face. Further, a surface on a
side of projecting the locking projection 35 is a face on a side
opposed to a side of forming the surface treatment coating 41 and
is a matrix metal face having a conductivity. Therefore, by
bringing the locking projection 35 having the conducted face into
contact with the inner peripheral face of the locking hole 31
constituting the conducted face, the front plate 13 and the face
plate of the inner box main body 23 are electrically connected and
an excellent radio wave shielding effect is achieved.
Further, with regard to the locking hole 31 and the locking
projection 35, when it is not necessary to electrically connect the
face plates to be bonded and a problem of a positional shift, a
bonding strength or the like is not severe at all, there may be
constructed a constitution dispensing with the locking hole 31 and
the locking projection 35. In this case, a simple bonding structure
can be constituted.
Next, an explanation will be given of a method of integrating the
above-described inner box for a cooker.
FIG. 6 shows a disassembled view of the inner box for a cooker and
FIG. 7 shows an example for bonding the inner box main body and the
ceiling plate.
The inner box main body 23 is formed by constituting a frame member
having a section in a rectangular shape by the side plates 21, 21
and the bottom plate 15 by pressing one sheet plate and bonding the
ceiling plate 17 to a side of an opening of the frame member (an
upper face in the drawing) by calking to bond or welding by spot
welding, or by engaging a locking claw 43 and a locking hole 45 as
shown in FIG. 7. The inner box main body 23 bonded with the four
faces is made to overlap the peripheral edge portion of the opening
portion 11 of the front plate 13 to bring respective end portions
of the four faces into a meshed state as shown by FIG. 3. That is,
there is constituted a state of inserting the flange portions 33 of
the respective face plates of the inner box main body 23 into the
clearances 29. Further, sides thereof are successively calked to
bond by the calking jig side by side.
According to such an integrating method, even when the sides are
successively calked to bond side by side, the sides are not shifted
relative to contiguous ones of the face plates in the height
direction as mentioned above and therefore, the sides can be bonded
without producing warping by the height shift. Further, the
pressure required for the calking step is made to be smaller than
that in the case of simultaneously calking to bond the four sides
to the front plate 13 after bonding four sheets of the face plates
of the inner box main body 23. Therefore, the calking step can be
carried out by a small-sized pressing apparatus, large-sized
formation of the calking apparatus is restrained and an integrating
step can be carried out at low cost. Further, with regard to the
method of integrating the inner box main body 23, other than the
above-described method, a section in a shape of a square cylinder
may be constituted by pertinently bonding the face plate to the
frame member having three sides of square, further, the invention
is not limited to the section having tree sides but the section in
the shape of the square may finally be formed by pertinently
combining single sheets of the face plates or two sheets or more of
the face plates. That is, the inner box main body 23 may be
integrated by a most pertinent method from various integrating
methods in consideration of a purpose of use, a material, a
fabrication efficiency or the like of the inner box, and even a
method other than the integrating method exemplified in the
embodiment can be provided to the invention without hindrance.
According to the inner box for a cooker explained as described
above, in bonding plate members in right angle as in bonding the
face plate of the inner box main body 23 to the front plate 13,
whereas at least either one of the bonding portions of the front
plate 13 and the inner box main body 23 is formed with the first
fold-to-bend portion constituted by folding to bend the end portion
to invert to be brought into close contact therewith and the second
fold-to-bend portion constituted by inverting the portion on the
side of the end portion of the first fold-to-bend portion with the
predetermined clearance therebetween, other of the bonding portions
of the front plate 13 and the inner box main body 23 is formed with
the flange portion inserted into the clearance between first
fold-to-bend portion and the second fold-to-bend portion and the
bonding portions of the front plate 13 and the inner box main body
23 are constituted by the structure in which the flange portion is
inserted into the clearance to be calked to bond, thereby, the
calking step can be carried out without requiring a large-sized
equipment and fabricating cost can be restrained.
That is, there is provided the calking step of bringing the second
fold-to-bend portion 27 into press contact with the first
fold-to-bend portion 25 via the flange portion 33 in a state in
which the flange portion 33 is brought into contact with the first
fold-to-bend portion 25 which has already been formed to fold to
bend and therefore, calking is carried out at a position at which
the face plate of the inner box main body 23 is brought into
contact with the front plate 13 and there is hardly a positional
shift between the face plate and the front plate 13 between before
calking and after calking. That is, no influence is effected to the
contiguous face plate. Further, calking is not carried out in one
motion to the entire periphery of the bonding portion by the large
pressure but calking is carried out separately and therefore,
bonding is carried out by comparatively small pressure. Therefore,
an integrating process can be simplified without needing a large
amount of equipment investment.
Further, the second fold-to-bend portion 27 is formed with the
locking hole 31, the flange portion 33 is formed with the locking
projection 35 to be inserted into the locking hole 31 and
therefore, even when an unconductive surface treatment is carried
out on the surface of the front plate 13 or the inner box main body
23, a conductive path is formed by the locking hole 31 of the front
plate 13 and the locking projection 35 of the flange portion 33,
the radio wave shielding effect can be achieved without being
influenced by the insulating surface treatment coating. Further, by
bringing the locking projection 35 into face contact with the inner
peripheral face of the locking hole 31 by calking, conduction can
firmly be ensured. Further, by both of the locking hole 31 and the
locking projection 35, the shift in the bonding position is
difficult to be brought about.
Next, an explanation will be given of a second embodiment of an
inner box for a cooker according to the invention. FIG. 8 is a
sectional view of an example for constituting a locking projection
formed at a flange portion by a drawn round hole projection.
According to the embodiment, a drawn round hole projection 47
having an opening hole is formed at an end portion of a face plate
of a inner box main body by drawing and the drawn round hole
projection 47 is inserted into the locking hole 31 of the front
plate 13 to be calked to bond. In this way, the shape of the
locking projection may be constituted by a shape brought into
contact with the inner peripheral face of the locking hole 31 to
lock to thereby achieve operation and effect similar to
above-described.
Further, the inner box for a cooker according to the invention is
not limited to the above-described embodiments but can pertinently
be modified or improved. For example, similar operation and effect
are achieved even when the front plate 13 is formed with the flange
portion and the respective face plates of the inner box main body
are formed with the first fold-to-bend portions and the second
fold-to-bend portions to combine.
According to the inner box for a cooker of the invention, whereas
at least one of the bonding portions of the front plate and the
inner box main body is formed with the first fold-to-bend portion
constituted by folding to bend the end portion to invert to be
brought into close contact therewith and the second fold-to-bend
portion constituted by inverting the portion of the side of the end
portion of the first fold-to-bend portion with the predetermined
clearance therebetween, other of the bonding portions of the front
plate and the inner box main body is formed with the flange portion
inserted into the clearance between the first fold-to-bend portion
and the second fold-to-bend portion and the bonding portions of the
front plate and the inner box main body are constituted by the
structure of inserting the flange portion into the clearance to be
calked to bond, thereby, the positional shift of the face plate is
not brought about between before and after the calking step and the
calking step can simply be carried out.
Further, according to the method of integrating the inner box for a
cooker, by bonding four sheets of the face plates to be connected
with the front plate to the front plate individually for the
respective face plates, the calking step can be carried out by a
comparatively small pressure without requiring a large-sized
equipment and the fabricating cost can be restrained.
* * * * *